Late-course hypofractionated stereotactic radiotherapy for locally advanced non-small cell lung cancer

Abstract

To evaluate the effect of late-course hypofractionated x-ray stereotactic radiotherapy on locally advanced non-small lung cancer. From October 1997 to June 1999, 106 patients with locally advanced non-small cell lung cancer were randomized into conventional radiotherapy group (CRT) and late-course hypofractionated stereotactic radiotherapy group (LCHSRT). Owing to distant metastases in course of radiotherapy or other reasons, 15 patients were excluded. Finally, 91 patients with intact data were analyzed, 43 patients were from the CRT group, 48 patients were from the LCHSRT group. In the CRT group, 18 patients were staged IIIa and 25 were staged IIIb; in the LCHSRT group, 19 patients were staged IIIa and 29 were staged IIIb. For patients in the CRT group, AP-PA fields which covered the primary tumor, ipsilateral pulmonary hilar region and mediastinum were given first with a dose fraction of 1.8-2Gy. After a median dose of 43.5Gy, the boost fields which covered the residual primary and metastatic regional lymph nodes were given with a dose faction of 1.8–2.0Gy, and the total median dose was increased to 65.2Gy. For patients in the LCHSRT group, AP-PA fields which covered the same region as in the CRT group were given first with a dose fraction of 1.8–2.0Gy. After a median dose of 44.4Gy, the late-course hypofractionated stereotactic radiotherapy was given to irradiate the residual primary and metastatic lymph nodes. The patients were immobilized in the vacuum bag with free uniform breath, and the GTV was delineated on the CT images. For the primary, the CTV was delineated with a margin of 5–8mm based on the GTV, the PTV was outlined with a margin of 10–15mm based on the CTV and the breath movement viewed on simulation unit; for the metastatic lymph nodes, the CTV were defined as the GTV, and the PTV was outlined with a margin of 5–8mm based on the CTV. The prescribed dose of 4-7Gy were given thrice weekly and delivered by noncoplanar arc irradiation with round cone beam collimator, total dose of 16-28Gy was given. The rates of symptomatic radiation-induced pneumonitis were 11.6% and 14.6%, respectively in the CRT and LCHSRT group. The rates of radiation-induced pulmonary fibrosis viewed on the CT images got in 6 months after radiotherapy were 48.8% and 66.7%, respectively in two groups, but there was statistically significant difference between the rates for patients who received the dose less than 20 Gy and more than 25Gy delivered by stereotactic radiotherapy, they were 30.7% and 91.3%, respectively. The rates of complete regression (CR) evaluated by CT scan 3 months after radiotherapy were 30.2% and 63.5%, respectively in the two groups. The 1-year local tumor control rates were 62% and 86.5%, respectively in two groups. The 1-year survival rates of the patients were 55.8% and 79.2%, respectively in two groups, there was statistically significant difference, but there was no statistically significant difference between the two groups in 2-year survival rates, 34.8% and 45.8%, respectively. Late-course hypofractionated stereotactic radiotherapy can improve 1-year survival rate of the patients with locally advanced non-small lung cancer, but it seems no benefit on the 2-year survival rate. Late-course hypofractionated stereotactic radiotherapy does not increase the rate of radiation-induced pneumonitis and pulmonary fibrosis. Stereotactic radiotherapy delivered by round collimator arc irradiation should not be used for the patients with tumor more than 5 cm in dimension, especially for erose tumor, because there is unacceptable dose ununiformity and unconformity